Field of the Invention
Described herein are guiding instruments for use in surgical procedures involving the positioning of a bone plate. Furthermore methods for the manufacture of such guiding instruments and methods for positioning a bone plate are also provided.
Description of the Related Technology
In complex surgeries like corrective osteotomies or acute trauma surgeries, the surgeon wants to correct a malunion, a congenital deformity or the like, to relieve pain or to improve the functionality of a part of the patient anatomy. The quality of the end result highly depends on the accuracy achieved during the surgical procedure.
For a number of years, the combination of virtual pre-operative planning and patient-specific surgical instruments has been available for performing complex orthopedic surgeries. This combination allows the surgeon to meticulously plan the surgery in advance on a virtual 3D model, and then execute this planning in the operating room by using patient-specific surgical instruments, which are unique to the patient and the planned surgery. The patient-specific instruments typically fit on a part of the patient anatomy and guide the surgeon in making osteotomies, in drilling and placing pins and screws.
For corrective osteotomies, the patient-specific instruments typically allow the surgeon to accurately pre-drill holes for the screws that will hold an osteosynthesis plate and to accurately make the osteotomy according to the pre-operative planning. The reduction of the bone fragments is then performed by attaching the osteosynthesis plate using the pre-drilled screw holes. Various types of osteosynthesis plates are available, such as standard compression plates, patient-specific plates and locking plates.
When using standard compression plates, the pre-operative planning should be made such that the plate contacts the bone. However, in the case of corrective osteotomies, one is typically dealing with abnormal anatomy, such that a stable contact between the plate and the bone fragments cannot always be guaranteed.
An alternative is to use a patient-specific plate. Such a plate can be designed to fit the patient anatomy in a stable manner. However, patient-specific implants are expensive to engineer and manufacture. Moreover, the plate can cause bone necrosis if the fit is too snug.
For these reasons, many surgeons prefer using locking plates and screws. In such systems, the screw holes provided on the plate and the screw heads are threaded, such that the screws can interlock with the plate. This allows attachment of the osteosynthesis plate without it making full or even any contact with the bone. However, the use of locking plates also has certain disadvantages. For example, without a stable contact between plate and bone, it is impossible for the surgeon to guarantee the same relative end positions of plate and bone fragments that were planned pre-operatively. Moreover, it is difficult to position the screws in the pre-operatively planned direction, even with pre-drilled holes for the screws. Indeed, although pre-drilling allows the surgeon to accurately find the correct entry point through the cortical bone, screws can easily divert from the pre-drilled tunnel in the trabecular bone. This is particularly problematic for angularly stable locking plates.
Accordingly, there is a need for improved methods for performing a corrective osteotomy, and for positioning of bone plates in general.